visiting a real reef

Observations while visiting a real reef

I’m a lucky guy. I just got back from a trip to Hawaii, where I got to do a lot of snorkeling.

visiting a real reef

It was cool to get to see the reefs in action. Real reefs around the big island of Hawaii. Here are a few things I observed:

Reef fishes are everywhere in Hawaii–it is truly paradise

In Hawaii, reef fishes are everywhere. You could see the glow from yellow tangs in the shallowest water right up to the shoreline. It was awesome.

Tangs, Tangs and more Tangs…and when you ran out of tangs there were Parrotfish

I’ve always wanted to have a few tangs in my aquarium because I always thought it looked more natural. Boy was I wrong. Ok, well not wrong, but here’s a look at what natural looks like:

cool huh?

Another impressive thing was the number of really big parrotfish I saw. They were big and they were also everywhere.


How can they grow coral with so many parrotfish? They are everywhere, like aquarium teenage boys with the superpower to eat everything in sight and poop out sand. Didn’t you know that’s where sand comes from? Check out this article from the Huffington Post.

In all seriousness, it made me wonder if we play the role of parrotfishes in our tanks when we frag our corals. From the looks of it, large fish are munching on the corals pretty much all the time.


There was also a fair amount of aggression on the reef–and almost exclusively from solo fish protecting their spot on the rocks when another fish (didn’t have to be a conspecific) swam by. The big shoals, on the other hand, seemed to flow effortlessly through the water almost like a single organism. But the lone wolfs played king of the mountain and chased off any passers-by routinely. The interesting thing is that the interloper most often just swam off–which is probably why we have so many problems with aggression in our aquaria–there is nowhere for the other fish to go.

Loss of coral reefs

Not everything was in abundance (at least where I snorkeled). I’ve read a lot about the destruction of reefs—but it was humbling to see the dead coral skeletons littering the reefs.
The reefs were not dead, per se. There was still a relatively significant amount of coral growth, but the reef appeared to be in a stage of transformation.

The rocks and reefs were predominantly colonized by massive (not branching) SPS—but you could see the (mostly) dead skeletons of the branching SPS on the rocks.

I was hoping to see much more variety in corals but the shallow reefs I visited were largely dominated by either encrusting or massive type growth forms. By the way, it’s harder to take clear pictures underwater than you would think :).

From the looks of it—and I am hypothesizing here—it seemed like the branching species had largely died back, while the massive species continued on. The colonies and dead skeletons were both rather large, which suggests to me the survivors were not ‘new’ to colonize, but rather likely they were growing together previously. Anyway, that’s my hunch.


Another interesting thing to see was how many sea urchins there were—there were urchins tucked in little crevices everywhere.

They clearly play a big role in maintaining the reef. A much bigger role than I had ever given them credit for. I had historically kept these algae munchers out of my tank (except for one failed experiment), but now I’m wondering if I should add them to my tank.

Not a lot of algae in sight

Problem algae? Not on the Hawaii reefs. It seemed to me that everything was eating film algae. As fast as the algae could grow, there was either a tang, butterflyfish, urchin or even sea turtle there to eat it.

Some of the rocks in the more sandy areas (where the sand would get kicked up by waves…or snorkelers…) were a bit ‘fuzzy’ covered by the sand, detritus and algae, but many of the reef areas seemed flawless, when it came to algae, yet all the veggie eaters were fat, very fat by reef tank standards and were grazing constantly, despite the fact that there were no tufts or pockets of algae—everything had the same thin coating (I assume) that was not visible from the surface.

The only hint of problem algae was actually from consumption warnings tied to some of the reef fish. There’s a type of poisoning called ciguatera poisoning, which is when humans get poisoned with a toxin called ciguatoxin which is found in the flesh of some reef fishes and those apex predators who eat the reef fishes.

It turns out that ciguatoxin comes from the ingestion of microalgae named Gambierdiscus. So people who eat the fish with an appreciable amount of that toxin built up in their flesh can become quite sick.

Other than that, I was surprised at how little algae there were. Guess I gotta do a much better job keeping my tank clean. The reef fishes never stopped picking on the rocks—and there were urchins in (nearly) every crevice. It makes me wonder if we as a hobby would have ‘cleaner’ tanks with higher densities of the veggie eating fish and inverts (assuming we could compensate appropriately for filtration). I’ll have to marinate on that idea for a while.

Temperature changes were dramatic yet irrelevant

The golden rule in aquarium keeping is to avoid swings in temperature because it is one of the most important water parameters. The old adage is that the ocean is a remarkably stable environment—and therefore our goal is to keep our reef tank environments equally stable. While that’s probably true about some of the parameters, I’ve personally suspected the temperature issue was a bit overblown, based on my experiences of non-issues during power failures (and watching the temperature drop).

However, I was blown away by the major temperature swings I experienced while snorkeling on the reefs.

Not from day-to-day swings, but from the strange mixing of cold and warm water on the reef. True, the ocean temperature itself appeared stable, but there were areas where water cold enough to make me shiver (and want to get out) were mixing with the warm ocean water. Swim just a few feet in the other direction and the water was fine. The changes were so dramatic you could see the temperature change visibly. This is called a thermocline. In the cold water areas the coral and fish were acting completely normal, seemingly oblivious to the temperature changes which were freezing me out.

Conclusion from a recent visit to a real reef

I’m very excited about the trip and know I’m privileged to have had a chance to snorkel in several of the best spots in Hawaii. It is an awesome and humbling experience to see how large and beautiful the reefs truly are. I suppose I’m walking away from this experience with a few conclusions:

  1. Temperature change (at least from warm to cold) didn’t appear to have a short-term effect, that I could observe. I suppose that might be a naive conclusion on my part, but the water was cold…I tell you… and then got right back to warm a few feet over.
  2. Fragging corals and pruning them back is as natural as watching a bunch of parrotfish chomp away…so I’m going to try to stop being so squeamish when I hack into my prized friends
  3. Instead of thinking about a cleanup crew, I might tweak that concept to look into a grazing crew. Urchins are apparently a big deal :).

Thanks for reading. I hope you enjoyed seeing some of the pics.


  1. Amazing, thank you. I do not think that urchins in an aquarium reaf environment is a good idea.

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